[Correlation between mismatch repair proteins status and clinicopathological characteristics in sporadic colorectal cancer patients].

Objective: To explore the expression of mismatch repair (MMR) proteins in sporadic colorectal cancer (SCRC) patients, and its association with clinicopathological characteristics of SCRC. Methods: Patients with histologically confirmed colorectal cancer were consecutively recruited between December 2011 and June 2015 at Sun Yat-sen University Cancer Center. The exclusion criteria included multiple primary colorectal tumors, hereditary colorectal cancer (including Lynch syndrome, familial adenomatous polyposis), and the patients without the MMR proteins status tested. A total of 2 684 patients were included. Correlations of MMR proteins status and patients' demographics (including gender, age), tumor characteristics (site and differentiation) and TNM staging (excluding 315 SCRC patients receiving neoadjuvant therapy) were investigated. Results: The percentage of deficient MMR (dMMR) in these SCRC patients was 10.2%, and that of proficient MMR (pMMR) was 89.8%. The dMMR was more likely to be detected in younger (≤59 old years) SCRC patients compared to the elderly (>59 years) [12.7%(179/1 406)vs 7.5%(96/1 278), P<0.001]. The dMMR rate in right colon cancer was significantly higher than that in left colon cancer and rectal cancer [22.7%(151/664)vs 7.2%(69/956)vs 5.2%(55/1 064), P<0.001]. Among the various pathological types of SCRC, mucinous adenocarcinoma showed the highest rate of dMMR (24.4%), and neuroendocrine carcinoma the lowest rate of dMMR (0) (P<0.001). In addition, the proportions of dMMR in stage Ⅰ, stage Ⅱ, stage Ⅲ and stage Ⅳ SCRC were 9.7%, 16.5%, 8.5%, and 3.9%, respectively (P<0.001). There is no significant difference in the proportion of dMMR between male and female (11.0% vs 9.1%, P=0.114). Conclusion: dMMR status may be most likely to exist in younger (≤59 years) patients with stage Ⅱ right colon mucinous adenocarcinoma among SCRC.

Water's potential role: Insights from studies of the p53 core domain.

Soluble proteins with amyloidogenic propensity such as the tumor suppressor protein p53 have high proportion of incompletely desolvated backbone H bonds (HB). Such bonds are vulnerable to water attack, thus potentially leading to the misfolding of these proteins. However, it is still not clear how the surrounding solvent influences the protein native states. To address this, systematic surveys by molecular dynamics simulations and entropy analysis were performed on the p53 core domain in this work. We examined seven wild/mutant X-ray structures and observed two types of water-network hydration in three "hot hydration centers" (DNA- or small molecule- binding surfaces of the p53 core domain). The "tight" water, resulting from the local collective hydrogen-bond interactions, is probably fundamental to the protein structural stability. The second type of water is highly "dynamical" and exchanges very fast within the bulk solution, which is unambiguously assisted by the local protein motions. An entropy mapping of the solvent around the protein and a temperature perturbation analysis further present the main features of the p53 hydration network. The particular environment created by different water molecules around the p53 core domain also partly explains the structural vulnerabilities of this protein.

Insight into the structural requirements of benzothiadiazine scaffold-based derivatives as hepatitis C virus NS5B polymerase inhibitors using 3D-QSAR, molecular docking and molecular dynamics.

Hepatitis C virus (HCV) infection is a significant world health threat with frequently ineffective problem existed in the present treatment, thus representing a major unmet medical need. The nonstructural viral protein 5B (NS5B), one of the best-studied polymerase, has emerged as an attractive target for the development of novel therapeutics against hepatitis C virus. In this work, both ligand- and receptor- based three-dimensional quantitative structure activity relationship (3D-QSAR) studies were carried out using comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) techniques on 360 benzothiadiazine scaffold-based derivatives as HCV GT-1b NS5B polymerase allosteric inhibitors. The resultant optimum 3D-QSAR model exhibited R(2)(ev) of 0.54, R(2)(nev) of 0.72 and the predictive ability was validated by using an independent test set of 90 compounds which gave R(2)(pred) value of 0.64. In addition, docking analysis and molecular dynamics simulation (MD) were also applied to elucidate the probable binding modes of these inhibitors at the allosteric site of the enzyme. Interpretation of the 3D contour maps in context of the topology of the allosteric binding site of NS5B provided insight into NS5B-inhibitor interactions. The information obtained from this work can be utilized to accurately predict the binding affinity of related analogues and also facilitate the future rational design of novel inhibitors with improved activity.